Many portable electronic devices, such as smart phones and tablet computers, include a touch sensitive display. The display typically includes part of a stack of components that includes a display screen, a touch sensitive layer overlaying the display screen and an outer monolithic transparent glass sheet, often referred to as a “cover glass,” that protects the display and touch sensitive layer. As the cover glass is a portion of the outer enclosure of the electronic device, the cover glass needs to be strong and resistant to scratches and other damage that can occur if the portable electronic device is dropped or if the display region undergoes an impact event.
The cover glass used for many portable electronic devices is typically made of a chemically-strengthened glass that provides improved fracture resistance to certain drop and impact events as compared to standard glass. The strengthened glass is, however, inherently softer than some other material options, which can lead to scratches formed on the surface of the glass that are detrimental to both user perception and to the reliability of the cover glass, as the scratches can reduce the fracture strength of the glass.